Each coin is stored on a different Unique wallet, The reason is that each coin is operating by a different blockchain, Never send coins if you are not sure where or who to send it to. When block-chain transactions are finalized they are irreversible and could be the cause for lost coins.

The entire philosophy behind crypto currency is to decentralized, meaning to eliminate 3rd parties involved. When purchasing bitcoin or others, we create a personal wallet, that no one but us can have access to it. If a broker ask you to deposit money to his account and he will open the wallet for you and will hold the coins for you, this is already a red flag. Again you are the only one that needs to know your private key.

Once a block-chain transaction if finalized it is impossible to reverse it back. Unlike our credit-card system or banking system, decentralized money is uninsured by a 3rd party, therefore the peers are there to make sure side A have the amount of Crypto-currency he wishes to send to side B but the peer system is not responsible for insuring where that money is sent to. Crypto-currency is in the responsibility of its holder and holder alone.